Hip and groin pain has for many years been a difficult diagnostic challenge. In the past decade there has been increased focus on femoroacetabular impingement (FAI) as a cause. FAI is now considered by many as a primary cause of hip joint degeneration.
The hip joint is a “ball-and-socket” joint located where the femur (thigh bone) meets the pelvic bone (FIG. 1). The upper segment (“femoral head”) of the femur is a round ball that fits inside the cavity of the pelvic bone that forms the socket, also known as the acetabulum. The femoral head is held in the acetabulum by a network of ligaments that form a capsule around the joint. This capsule of ligaments contains synovial fluid which acts as a lubricant. A smooth cartilage covers the femoral head and the acetabulum and provides a smooth, low friction surface that allows the bones to glide easily across each other. The acetabulum is lined with a fibrocartilage termed labrum which forms a gasket around the acetabulum ensuring a snug fit of the femoral head within the acetabulum.
In FAI, bone overgrowth develops around the femoral head and/or along the acetabulum, causing the bones to hit against each other, rather than to move smoothly. Over time, this repetitive impact can result in the tearing of the labrum and breakdown of the cartilage (osteoarthritis).
There are three main types of FAI: (1) Cam impingement, (2) Pincer impingement, and (3) a combination of Cam and Pincer impingement. In Cam impingement, excess bone forms around the femoral head, such that the femoral head is not round and cannot rotate smoothly inside the acetabulum. In Pincer impingement, excess bone extends out of the acetabulum, which may damage the labrum, or the acetabulum is angled in such a way that abnormal impact occurs between the femoral head and the acetabulum. Cam impingement typically affects young males while Pincer impingement is more common among older females. Morphologic abnormalities of the bones may predispose a patient to FAI. Sporting activities, such as the ones that involve a repetitive axial load through the hip or frequent pivoting movements resulting in torsional forces, may contribute to the development of FAI lesions, although the exact mechanism by which this happens is unclear.
As a result of abnormal impact between the femoral head and the acetabulum, the femoral head does not have its full range of motion within the acetabulum. Symptoms of FAI include pain in the groin and hip area, restricted range of hip joint motion, progressive muscle weakness and reduced flexibility.
Current therapies for FAI include anti-inflammatory medications and activity modifications, steroid injections, and surgical options. Anti-inflammatory medications, including non-steroidal anti-inflammatory drugs (NSAIDS) such as aspirin and ibuprofen; and opioids, and activity modification may provide short term relief but do not address the underlying problem. Steroid injections have long term side effects, including cartilage break down. Surgical options, such as open, arthroscopic and combined techniques, are intensive, and involve long recovery period.
Thus, there is a need for alternative treatment methods that treat or alleviate symptoms associated with FAI.